First serial hybrid electric aircraft takes off

21 June, 2011

The world`s first aircraft with a serial hybrid electric drive system has made its debut at the 2011 Paris Air Show in Le Bourget, France. The two-seater DA36 E-Star motor glider has been built by a consortium of Siemens, the Austrian aircraft manufacturer Diamond Aircraft and the aerospace contractor EADS to test a hybrid electric drive system which, they say, could cut fuel consumption and emissions by 25%.

The plane (above), based on Diamond’s HK36 Super Dimona powered glider, is the first aircraft to use a serial hybrid electric drivetrain of a type previously used only in cars.

The plane`s propeller is driven by a 70kW Siemens motor powered by a 30kW Austro Engine Wankel engine, with a generator that functions solely as a power source. An EADS battery system supplements the power for takeoff and climbing, and is recharged during the cruising phase. The motor is powered from the battery and generator via a Siemens converter. Because the engine runs constantly with a low output, fuel consumption is low.

“A serial hybrid electric drive can be scaled for a wide range of uses, making it highly suitable for aircraft as well,” says Dr Frank Anton, the initiator of electric aircraft development at Siemens. “The first thing we want to do is test the technology in small aircraft. In the long term, however, the drive system will also be used in large-scale aircraft. We want to cut fuel consumption and emissions by 25%, compared to today`s most efficient technologies. This will make air travel more sustainable.” Air traffic currently accounts for about 2.2% of global CO2 emissions.

The electric motor glider completed its maiden flight in Austria on 8 June. “On the long way to hybrid electric-powered commercial aircraft, the maiden flight of the DA36 E-Star is a small step and at the same time a historic milestone,” says EADS’ chief technical officer, Dr Jean Botti.

The partners now plan to optimise the hybrid drivetrain. Siemens is working on a new electric motor that it expects will be five times lighter than conventional drives. An aircraft equipped with this motor is expected to take off in about two years’ time.